A Comparison Study on Control Moment Gyroscope Arrays and Steering Laws

Current reaction wheels and magnetorquers for microsatellite are limited by low slew rate and heavily depends on orbital parameters for coverage area. Control moment gyroscope (CMG) clusters offer an alternative solution for high slew rates and rapid retargeting. Though CMGs are often used in large space missions, their use in microsatellites is limited due to the stringent mass budget. Most literature reports only on pyramid configuration, and there are no definite cross-comparison studies between various CMG clusters and steering laws. In this research, a generic tool in Matlab and Simulink is developed to further understand CMG configurations and steering laws for a microsat mission. Various steering laws necessary for mitigating singularities in CMG clusters are compared in two distinct missions. The simulation results were evaluated based on the pointing accuracy, platform jitter, and pointing stability achieved by the spacecraft for each combination of CMG clusters, and steering laws and trajectories. The simulation results demonstrate that the pyramid cluster is marginally better than the rooftop cluster in pointing accuracy. The comparison of steering laws shows that, counterintuitively, Singularity Robust steering law, which passes through singularities, outperforms both Moore-Penrose and Local Gradient methods for almost all evaluation criteria for the two missions it was tested on. The simulation results would aid systems engineers in designing low-cost actuation systems and corresponding control software, which can increase the data acquisition rate of remote sensing missions

Advances in Rotating Electric Machines

It is difficult to imagine a modern society without rotating electric machines. Their use has been increasing not only in the traditional fields of application but also in more contemporary fields, including renewable energy conversion systems, electric aircraft, aerospace, electric vehicles, unmanned propulsion systems, robotics, etc. This has contributed to advances in the materials, design methodologies, modeling tools, and manufacturing processes of current electric machines, which are characterized by high compactness, low weight, high power density, high torque density, and high reliability. On the other hand, the growing use of electric machines and drives in more critical applications has pushed forward the research in the area of condition monitoring and fault tolerance, leading to the development of more reliable diagnostic techniques and more fault-tolerant machines. This book presents and disseminates the most recent advances related to the theory, design, modeling, application, control, and condition monitoring of all types of rotating electric machines

Recent Advances in Robust Control

Robust control has been a topic of active research in the last three decades culminating in H_2/H_\infty and \mu design methods followed by research on parametric robustness, initially motivated by Kharitonov's theorem, the extension to non-linear time delay systems, and other more recent methods. The two volumes of Recent Advances in Robust Control give a selective overview of recent theoretical developments and present selected application examples. The volumes comprise 39 contributions covering various theoretical aspects as well as different application areas. The first volume covers selected problems in the theory of robust control and its application to robotic and electromechanical systems. The second volume is dedicated to special topics in robust control and problem specific solutions. Recent Advances in Robust Control will be a valuable reference for those interested in the recent theoretical advances and for researchers working in the broad field of robotics and mechatronics

An assessment of flywheel storage for efficient provision of reliable power for residential premises in islanded operation

Energy storage systems (ESS) are key devices for improving power quality, electrical system stability and system efficiency by contributing to the balance of supply and demand. They can enhance the flexibility of electrical systems by mitigating supply intermittency, which has recently become problematic due to the increased penetration of renewable generation. The subject of this thesis is flywheel energy storage system (FESS), a technology that is gathering great interest due to benefits offered over alternative energy storage solutions, including high cycle life, long calendar life, high round‐trip efficiency, high power density, operation at high ambient temperatures and low negative environmental impact. This thesis describes the modelling and assessment of small scale energy system incorporating FESS with solar photovoltaic (PV) and a diesel generator for use in islanded residential premises with highly intermittent or non‐existent grid infrastructure. In this application, incorporation of FESS is shown to be beneficial in comparison to a system without storage or one with the alternative storage technology, Li‐Ion batteries. The thesis begins with a description of flywheel storage systems configured for electrical storage which comprises of a mechanical part; flywheel rotor, bearings and containment, and an electric drive part; motor‐generator and associated power electronics. Each of these components is described in the thesis along with the equations and modelling, itself carried out in the MATLAB/Simulink environment. Finally, the flywheel model is combined with a model of an islanded residential power system incorporating a solar PV system with a diesel generator. Such a system would be particularly useful for offgrid applications or those with weak grids as occurs in developing countries

9th EASN International Conference on Innovation in Aviation & Space

This Special Issue book contains selected papers from works presented at the 9th EASN (European Aeronautics Science Network) International Conference on Innovation in Aviation & Space, which was held in Athens, Greece from the 3rd until the 6th of September, 2019. About 450 participants contributed to a high-level scientific gathering, providing some of the latest research results on the topic, as well as some of the latest relevant technological advancements. Eight interesting articles, which cover a wide range of topics including characterization, analysis and design, as well as numerical simulation, are contained in this Special Issue

Advances in Intelligent Vehicle Control

This book is a printed edition of the Special Issue Advances in Intelligent Vehicle Control that was published in the journal Sensors. It presents a collection of eleven papers that covers a range of topics, such as the development of intelligent control algorithms for active safety systems, smart sensors, and intelligent and efficient driving. The contributions presented in these papers can serve as useful tools for researchers who are interested in new vehicle technology and in the improvement of vehicle control systems

Development of an electric vehicle for autonomous use on a New Zealand dairy farm.

With the increasing cost of employment and difficulty finding suitably skilled workers, autonomous vehicles are being implemented as a solution across a number of industries. On New Zealand dairy farms, simplistic tasks such as transporting feed and supplies, mowing, spraying and pasture measurement could easily be completed by a small autonomous vehicle. Pasture measurement is particularly important to maximize the farm’s productivity, but is often neglected as it consumes a significant quantity of time. Consequently, there is real demand for an autonomous vehicle to complete these tasks. Ideally, this autonomous vehicle would be electric due to the reduced environmental impact, coupled with lower running costs, higher reliability and ease of control when compared to internal combustion (IC) equivalents. However, the major factors limiting the implementation of electric vehicles (EVs) in agriculture is their significantly smaller range (travel distance on one charge) and higher purchase price. For it to be worthwhile to utilize an EV to complete these autonomous tasks, it must produce a similar range when compared to an IC equivalent at a competitive price. It was identified during the EV’s development that producing the desired range was going to be very difficult due to the expensive nature of lightweight batteries limiting battery capacity. An EV was developed, similar in size to a typical IC quad, which focused on maximizing its efficiency and minimizing vehicle weight and cost, whilst remaining a capable off-road vehicle. The developed EV was significantly lighter than similar sized off-road EVs, with suspension, traction and steering characteristics that matched or exceeded the performance of IC equivalents. This means that a very capable off-road EV can be developed. The developed EV produced a maximum powertrain efficiency of 84%. However, even with this high efficiency, further work had to be completed to maximize range within the limited battery capacity. Due to the off-road environment and low operational speed of the EV, motion and rolling resistance are the only significant forces constantly opposing the EV’s motion. Motion resistance was investigated and it was determined that vehicle design and tyre selection had a major influence on the resistive forces experienced. A further study into rolling resistance was conducted, were it was found little was known about rolling resistance of small all-terrain vehicles (ATVs). Experiments were conducted and rolling resistance data was collected for seven ATV tyres. The obtained data confirmed and established relationships between rolling resistance, tyre properties, and operational and environmental conditions. It was determined that tyre selection has a major influence on the forces opposing the EV’s motion and, consequently, had a significant effect on the developed EV’s range. The developed EV produced a significantly larger range (travel distance on one charge) than similar sized off-road EVs despite its much smaller battery capacity. This was due to the significant reduction of rolling and motion resistance through appropriate tyre selection and vehicle design. The developed EV was competitive with an IC equivalent, producing a 20km lower range at approximately the same vehicle price. With further developments in battery technology and the reduction of battery prices, the developed EV will be able to match or exceed the range of IC equivalents to produce a more commercially viable autonomous vehicle

Nonlinear Systems

Open Mathematics is a challenging notion for theoretical modeling, technical analysis, and numerical simulation in physics and mathematics, as well as in many other fields, as highly correlated nonlinear phenomena, evolving over a large range of time scales and length scales, control the underlying systems and processes in their spatiotemporal evolution. Indeed, available data, be they physical, biological, or financial, and technologically complex systems and stochastic systems, such as mechanical or electronic devices, can be managed from the same conceptual approach, both analytically and through computer simulation, using effective nonlinear dynamics methods. The aim of this Special Issue is to highlight papers that show the dynamics, control, optimization and applications of nonlinear systems. This has recently become an increasingly popular subject, with impressive growth concerning applications in engineering, economics, biology, and medicine, and can be considered a veritable contribution to the literature. Original papers relating to the objective presented above are especially welcome subjects. Potential topics include, but are not limited to: Stability analysis of discrete and continuous dynamical systems; Nonlinear dynamics in biological complex systems; Stability and stabilization of stochastic systems; Mathematical models in statistics and probability; Synchronization of oscillators and chaotic systems; Optimization methods of complex systems; Reliability modeling and system optimization; Computation and control over networked systems